In order to study contrast agent flow, which is representative of blood flow, through vessels in an angiography image sequence, it is useful to generate a static representation of flow using a color spectrum to represent the time at which contrast agent reached a certain state within vessels (e.g., first entered, reached a peak, no longer seen). For angiography, a typical color spectrum uses red to represent early blood flow and blue to represent late blood flow. In order to generate optimum results, individual images in an image sequence need to be in substantially perfect registration with a mask image frame showing background image detail. An image comprising a static representation of flow is generated as a composite representation of images acquired over a particular time period. Therefore, image related motion that occurs due to, slight patient movement or slight X-ray table motion, for example, causes undesired mis-registration artifacts to appear in a resulting blood flow representative composite image. A system according to invention principles addresses the identified deficiencies and associated problems.